Powdered activated carbon (“PAC”) is a highly amorphous form of carbon having an average particle size of about −80 mesh (e.g., not greater than about 177 μm). PAC may be manufactured to have a high porosity, a small average pore size and a high surface area, and as such is able to bind (e.g., adsorb) many contaminant species from another substance, thereby purifying (e.g., decontaminating) the other substance.
Industrial applications of PAC include, but are not limited to, the treatment of waste-water, food purification, and treatment of flue gas from a boiler (e.g., a coal boiler). In treatment of flue gas, PAC acts to remove contaminants such as mercury. For many such industrial applications, PAC is shipped in bulk to an end user, such as by using trucks, rail shipment, or the like. The PAC is unloaded from the truck or rail car and may be placed subsequently in a storage unit (e.g., a storage silo). When the PAC is needed, it is then conveyed to the point of use, e.g., to a water treatment process or to a flue gas treatment process.
Often, the PAC is pneumatically conveyed, such as from a rail car to a storage unit, from a rail car to a transportation truck, or from a transportation truck to a storage unit, and/or from the storage unit to the point of use. Pneumatic conveyance of PAC involves conveying the PAC through an enclosed pipeline using a pressure differential and the flow of a gas (e.g., air) to suspend and move the PAC along the pipeline. Typically, the PAC is conveyed in a dilute phase, i.e., where the conveying system relies on the gas velocity to pick up and entrain the particles. Pneumatic conveyance of PAC has many advantages over other conveyance techniques. For example, pneumatic conveyance pipelines can be arranged with bends to circumvent other equipment, and the system has few moving parts and is completely enclosed.